Hello,
Thank you for your query and we are so sorry about the trouble this must have caused.
We have identified this issue and reported it to our development team. We will include a fix in a future update of the plugin.
For now, please replace the code on line 103 of this specific file seo-by-rank-math/includes/modules/schema/blocks/toc/class-block-toc.php with the code below:
$title_wrapper = isset( $parsed_block['attrs']['titleWrapper'] ) && in_array( $parsed_block['attrs']['titleWrapper'], $allowed_tags, true ) ? $parsed_block['attrs']['titleWrapper'] : 'h2';
That notice should go away.
Hope that helps and please do not hesitate to let us know if you need our assistance with anything else.
Hello,
We have released a Beta update that fixed the issue.
Please enable the Beta update by following this guide below:
https://rankmath.com/kb/version-control/#beta-updates

If you are unable to see an update, please clear Rank Math’s transients from:
WordPress Dashboard > Rank Math > Status & Tools > Database Tools > Remove Rank Math Transients > Remove transients

Please clear the caches, server, and WordPress after updating.
You can disable the Beta updates once you update to the latest version and the issue is fixed.
Thank you.
It worked inserting that line of code. Thanks.
Hello,
We’re delighted to hear that this issue has been resolved. We appreciate your feedback.
This ticket will be closed now, but if you ever have another question or need any help in the future, please don’t hesitate to create a new forum topic. We’ll be more than happy to assist you again.
Thank you for choosing Rank Math and have a wonderful day!